In recent years, the reduction of carbon dioxide emissions has been sincerely desired for the purpose of environmental protection. The automotive industry has a growing expectation on the introduction of electric vehicles (EV) and hybrid electric vehicles (HEV) for the reduction of carbon oxide emissions and has increasingly developed motor-drive secondary batteries, which become key to the practical application of these electric vehicles. Among the secondary batteries, attention is being given to lithium-ion secondary batteries of high energy density and high output density.
In the lithium-ion secondary battery, an electrode is generally formed by applying a positive electrode active material or negative electrode active material to a collector with the use of a binder material.
Conventionally, the collector of the lithium-ion secondary battery is a metal foil. As a substitute for the metal foil collector, a conductive resin-containing collector has recently been put into use. (See e.g. Japanese Laid-Open Patent Publication No. 61-285664.) The resin-containing conductive collector is lighter in weight than the metal foil collector and is thus expected to improve battery power output.